title: Protein and Mg(2+)-induced conformational changes in the S15 binding site of 16 S ribosomal RNA.
abstract: The Bacillus stearothermophilus ribosomal protein S15 binds to the central domain of the 16 S rRNA inducing a conformational change in a three-way helical junction. To understand the nature of this conformational change, extended-helical junctions were prepared to examine the effects of S15 or Mg2+ binding on the relative helical orientation using native gel electrophoretic mobility and transient electric birefringence. The free junction is planar with approximately 120 degrees interhelical angles, whereas S15 and Mg2+ yield a junction conformation that remains planar in which two helices, 21 and 22, become colinear and the third, helix 20, forms a 60 degrees angle with respect to helix 22. This conformational change is thought to be important for directing the assembly of the central domain of the 30 S ribosomal subunit.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Orr
authors.forename: P J
authors.initials: PJ
authors.lastname: Hagerman
authors.forename: J R
authors.initials: JR
authors.lastname: Williamson
mesh_terms: D001483:Base Sequence; D001665:Binding Sites / Q000187:drug effects; D004591:Electrophoresis, Polyacrylamide Gel; D001411:Geobacillus stearothermophilus; D008024:Ligands; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation / Q000187:drug effects*; D011485:Protein Binding / Q000187:drug effects; D012336:RNA, Ribosomal, 16S / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism / Q000502:physiology; D012269:Ribosomal Proteins / Q000378:metabolism / Q000502:physiology*
chemical_list: D008024:Ligands; D012336:RNA, Ribosomal, 16S; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; C036004:ribosomal protein S15; D008274:Magnesium